scholarly journals Evaluation of Static and Dynamic Residual Mechanical Properties of Heat-Damaged Concrete for Nuclear Reactor Auxiliary Buildings in Korea Using Elastic Wave Velocity Measurements

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2695 ◽  
Author(s):  
Seong-Hoon Kee ◽  
Jun Won Kang ◽  
Byong-Jeong Choi ◽  
Juho Kwon ◽  
Ma. Doreen Candelaria
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Elastic Wave ◽  
Wave Velocity ◽  
Elastic Moduli ◽  
Nuclear Reactor ◽  
Dynamic Properties ◽  
Velocity Measurements ◽  
Heating And Cooling ◽  
Dynamic Elastic Moduli

The main objectives of this study are (1) to investigate the effects of heating and cooling on the static and dynamic residual properties of 35 MPa (5000 psi) concrete used in the design and construction of nuclear reactor auxiliary buildings in Korea; and (2) to establish the correlation between static and dynamic properties of heat-damaged concrete. For these purposes, concrete specimens (100 mm × 200 mm cylinder) were fabricated in a batch plant at a nuclear power plant (NPP) construction site in Korea. To induce thermal damages, the concrete specimens were heated to target temperatures from 100 °C to 1000 °C with intervals of 100 °C, at a heating rate of 5 °C/min and allowed to reach room temperature by natural cooling. The dynamic properties (dynamic elastic modulus and dynamic Poisson’s ratio) of concrete were evaluated using elastic wave measurements (P-wave velocity measurements according to ASTM C597/C597M-16 and fundamental longitudinal and transverse resonance tests according to ASTM C215-14) before and after the thermal damages. The static properties (compressive strength, static elastic modulus and static Poisson’s ratio) of heat-damaged concrete were measured by the uniaxial compressive testing in accordance with ASTM C39-14 and ASTM C469-14. It was demonstrated that the elastic wave velocities of heat-damaged concrete were proportional to the square root of the reduced dynamic elastic moduli. Furthermore, the relationship between static and dynamic elastic moduli of heat-damaged concrete was established in this study. The results of this study could improve the understanding of the static and dynamic residual mechanical properties of Korea NPP concrete under heating and cooling.

Contribution of Collagen, Mineral and Water Phases to the Nanomechanical Properties of Bone

2004 ◽  
Vol 844 ◽  
Author(s):  
Amanpreet K. Bembey ◽  
Vanessa Koonjul ◽  
Andrew J. Bushby ◽  
Virginia L. Ferguson ◽  
Alan Boyde
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Cortical Bone ◽  
Material Properties ◽  
Elastic Moduli ◽  
Metacarpal Bone ◽  
Cortical Tissue ◽  
Direction Transverse ◽  
Nanomechanical Properties ◽  
Loading Direction

ABSTRACTCortical bone is an anisotropic material, and its mechanical properties are determined by its composition as well as its microstructure. Mechanical properties of bone are a consequence of the proportions of, and the interactions between, mineral, collagen and water. Mid-shaft palmar cortical tissue from the equine third metacarpal bone is relatively dense and uniform with low porosity. The mainly primary osteons are aligned to within a few degrees of the long axis of the bone. Beams of compact cortical bone were prepared to examine effects of dehydration and embedding and to study contribution of collagen and mineral to nano-scale material properties. Five beams were tested: untreated (hydrated); 100% ethanol (dehydrated); or embedded in poly-methylmethacrylate (PMMA) for one normal, one decalcified, and one deproteinated bone sample. Elastic modulus was obtained by nanoindentation using spherical indenters, with the loading direction transverse [1] and longitudinal to the bone axis. By selectively removing water, mineral and organic components from the composite, insights into the ultrastructure of the tissue can be gained from the corresponding changes in the experimentally determined elastic moduli.

ELASTIC‐WAVE VELOCITY MEASUREMENTS IN ROCKS AND OTHER MATERIALS BY PHASE‐DELAY METHODS

Geophysics ◽  
1975 ◽  
Vol 40 (6) ◽  
pp. 955-960 ◽  
Author(s):  
E. A. Kaarsberg
Keyword(s):  
Elastic Wave ◽  
Wave Velocity ◽  
Path Length ◽  
Shear Velocity ◽  
Elastic Wave Velocity ◽  
Phase Delay ◽  
Velocity Measurements ◽  
Multiple Reflections ◽  
Low Velocity ◽  
High Attenuation

The phase delay of a continuous sinusoidal elastic wave after transmission through a medium may be used to determine the velocity of propagation of the wave in the medium. The change in path length for a given frequency, or the change in frequency for a given path length, required to change the phase delay by integral multiples of 360 degrees is measured in the laboratory by the use of source and receiver piezoelectric transducers whose signals are applied to the horizontal and vertical deflection circuits of an oscilloscope. The accuracy of the method depends upon the accuracy with which the frequency of the transmitted wave and its path length through the medium (or change in path length) can be determined, provided the effect of extraneous signals (e.g., boundary reflections, multiple reflections, alternate modes of propagation, etc.) is negligible. The phase‐delay methods are illustrated and compared with conventional pulse methods by using both to make compressional‐velocity measurements in water and compressional‐ and shear‐velocity measurements in a high velocity basalt and in a low velocity dried mud sample. The results of the two methods agree to within a few percent. It is suggested that these phase‐delay methods may be especially well‐suited for making elastic‐wave velocity measurements in media with high attenuation of the waves propagated in them.

scholarly journals A Direct Comparison of Three Buckling-Based Methods to Measure the Elastic Modulus of Nanobiocomposite Thin Films

2020 ◽  
Author(s):  
Taylor C. Stimpson ◽  
Daniel A. Osorio ◽  
Emily D. Cranston ◽  
Jose Moran-Mirabal
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Mechanical Properties ◽  
Elastic Modulus ◽  
Elastic Moduli ◽  
Input Parameter ◽  
Layer By Layer ◽  
Free Standing ◽  
Film Composition ◽  
Parameter Values

<p>To engineer tunable thin film materials, accurate measurement of their mechanical properties is crucial. However, characterizing the elastic modulus with current methods is particularly challenging for sub-micrometer thick films and hygroscopic materials because they are highly sensitive to environmental conditions and most methods require free-standing films which are difficult to prepare. In this work, we directly compared three buckling-based methods to determine the elastic moduli of supported thin films: 1) biaxial thermal shrinking, 2) uniaxial thermal shrinking, and 3) the mechanically compressed, strain-induced elastic buckling instability for mechanical measurements (SIEBIMM) method. Nanobiocomposite model films composed of cellulose nanocrystals (CNCs) and polyethyleneimine (PEI) were assembled using layer-by-layer deposition to control composition and thickness. The three buckling-based methods yielded the same trends and comparable values for the elastic moduli of each CNC-PEI film composition (ranging from 15 – 44 GPa, depending on film composition). This suggests that the methods are similarly effective for the quantification of thin film mechanical properties. Increasing the CNC content in the films statistically increased the modulus, however, increasing the PEI content did not lead to significant changes. The standard deviation of elastic moduli determined from SIEBIMM was 2-4 times larger than for thermal shrinking, likely due to extensive cracking and partial film delamination. In light of these results, biaxial thermal shrinking is recommended as the method of choice because it affords the simplest implementation and analysis and is the least sensitive to small deviations in the input parameter values, such as film thickness or substrate modulus.</p>

Contribution of Collagen, Mineral and Water Phases to the Nanomechanical Properties of Bone

2004 ◽  
Vol 841 ◽  
Author(s):  
Amanpreet K. Bembey ◽  
Vanessa Koonjul ◽  
Andrew J. Bushby ◽  
Virginia L. Ferguson ◽  
Alan Boyde
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Cortical Bone ◽  
Material Properties ◽  
Elastic Moduli ◽  
Metacarpal Bone ◽  
Cortical Tissue ◽  
Direction Transverse ◽  
Nanomechanical Properties ◽  
Loading Direction

ABSTRACTCortical bone is an anisotropic material, and its mechanical properties are determined by its composition as well as its microstructure. Mechanical properties of bone are a consequence of the proportions of, and the interactions between, mineral, collagen and water. Mid-shaft palmar cortical tissue from the equine third metacarpal bone is relatively dense and uniform with low porosity. The mainly primary osteons are aligned to within a few degrees of the long axis of the bone. Beams of compact cortical bone were prepared to examine effects of dehydration and embedding and to study contribution of collagen and mineral to nano-scale material properties. Five beams were tested: untreated (hydrated); 100% ethanol (dehydrated); or embedded in poly-methylmethacrylate (PMMA) for one normal, one decalcified, and one deproteinated bone sample. Elastic modulus was obtained by nanoindentation using spherical indenters, with the loading direction transverse [1] and longitudinal to the bone axis. By selectively removing water, mineral and organic components from the composite, insights into the ultrastructure of the tissue can be gained from the corresponding changes in the experimentally determined elastic moduli.

Strain-Dependent Properties of Polymers I

1966 ◽  
Vol 39 (5) ◽  
pp. 1421-1427 ◽  
Author(s):  
G. E. Warnaka ◽  
H. T. Miller
Keyword(s):  
Loss Factor ◽  
Elastic Moduli ◽  
Dynamic Properties ◽  
Amorphous Polymers ◽  
Temperature Dependent ◽  
Strain Dependence ◽  
Self Heating ◽  
Dynamic Elastic Moduli ◽  
Temperature Dependent Properties ◽  
Strain Dependent

Abstract Dynamic elastic moduli of homogeneous, amorphous polymers decrease at moderate to high strains. Under the same strain magnitudes the loss factor goes through a broad maximum. At low strains, dynamic properties are independent of strain amplitude. This paper shows that strain dependence is a basic property of homogeneous, amorphous polymers. Strain dependence is shown to occur in gum, as well as filled, vulcanizates. In addition it is shown that self heating due to flexing at high strains cannot fully explain strain dependent dynamic properties. Testing has been performed on specimens with greatly varying geometries (and, hence, different amounts of self-heating) and at controlled specimen temperatures. These tests have verified the existence of a basic strain-dependency. Strain dependence is here related to time-temperature dependent properties of polymers as described by the well-known work of Williams, Landel, and Ferry. The magnitude of strain dependence and the strain amplitudes at which strain dependence occurs appear to be controlled by the time-temperature dependence of polymers.

scholarly journals Elastic Modulus, Thermal Expansion, and Pyrolysis Shrinkage of Norway Spruce Under High Temperature

2021 ◽  
Author(s):  
Tito Adibaskoro ◽  
Michalina Makowska ◽  
Aleksi Rinta-Paavola ◽  
Stefania Fortino ◽  
Simo Hostikka
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Elastic Modulus ◽  
Norway Spruce ◽  
Elastic Moduli ◽  
Elevated Temperatures ◽  
Ambient Air ◽  
Time Dependent ◽  
Temperature History ◽  
Direction Parallel

AbstractThe orthotropic and temperature-dependent nature of the mechanical properties of wood is well recognized. However, past studies of mechanical properties at elevated temperatures are either limited to temperatures below 200 °C or focus only on the direction parallel to grain. The effect of time-dependent pyrolysis during measurement is often neglected. This paper presents a novel method for determining elastic modulus at high temperatures and thermal expansion coefficient in different orthotropic directions via Dynamic Mechanical-Thermal Analyser (DMTA). The method allows for drying, drying verification, and measurement in one chamber, eliminating the possibility of moisture reabsorption from ambient air. The repeatable measurements can be carried out in temperatures up to 325°C, adequate for observing time-dependent pyrolysis during measurement. Results of the measurements of Norway Spruce provide data of its mechanical response at temperature range previously not explored widely, as well as in the orthotropic direction. Time-dependent behaviour was observed in the thermal expansion and shrinkage experiment, where above 250°C the amount of shrinkage depends on heating rate. At such temperature, elastic moduli measurement also shows time dependence, where longer heating at certain temperature slightly increases the measured elastic modulus. Additionally, bilinear regression of the relationship between elastic moduli and temperature shows quantitatively good fit. Numerical simulation of the DMTA temperature history and wood chemical components mass losses show the onset of shrinkage and onset of hemicellulose mass loss occurring at around the same time, while decomposition of cellulose correlate with the sudden loss of elastic moduli.

Sign in / Sign up

Export Citation Format

Share Document